The present invention relates to a printing plate material for a computer-to-plate (hereinafter referred to as CTP) system having an aluminum support, a plate-making method and a printing method.
In recent years, in manufacturing technologies of printing plates for offset printing, there have been developed CTPs for recording digital data of images directly on a photosensitive printing plate with a laser light source, and they have been put to practical use.
In the field of printing where relatively long plate life is required among the aforesaid technologies, there is known a method to use a printing plate material having thereon an aluminum plate representing a support and an image forming layer provided on the aluminum plate.
As the aluminum plate, there are generally used those subjected to surface-roughening treatment and anodic treatment.
On the other hand, there is a demand for a printing plate material that requires no photographic processing by a processing solution containing specific chemicals (for example, an alkali, an acid and a solvent), and can be applied to conventional printing machines, and for example, there are known printing plate materials for a dry CTP method such as a printing plate material of a phase changing type that does not require photographic processing at all and a printing plate material in which photographic processing is conducted in the initial stage of printing on the printing machine and does not require a development process in particular.
As those used for a dry CTP method, there are given, for example, printing plate materials of an abrasion type described in TOKUKAIHEI Nos. 8-507727, 6-186750, 6-199064, 7-314934, 10-58636 and 10-244773, and those of a type in which a thermosensitive image forming layer is provided on a base material and an image portion is formed on a hydrophilic layer through imagewise heat generation by laser exposure (for example, Patent Document 1, Patent Document 2 and Patent Document 3).
The printing plate material having a thermosensitive image forming layer for forming an image portion where a laser beam is converted into heat on a hydrophilic layer is suitable for forming a high-definition images, because sharp dots are formed.
As the printing plate material for CTP having relatively high plate life, there are known printing plate materials each having therein a photopolymerization type image forming layer described in, for example, TOKUKAI Nos. 2002-107916 and 2003-76010.
Since halftones are recorded with 100-300 lines of laser each being converged to 5-30 μm in CTP in general, an individual halftone is recorded with plural laser beams as a rule.
In a principle, therefore, it is possible to change gradation reproduction for printing optionally, by changing exposure pattern and output of laser exposure, thus, in conventional CPT printing, conditions of a plate-making apparatus are used after initial setting, so that desired printed matters may be obtained.
However, it has been necessary to prepare an exclusive plate-making apparatus respectively and to change condition setting manually, when using plural types and sizes of printing plate materials, because it is necessary to set a plate-making apparatus and plate-making conditions depending on types and sizes of printing plate materials for CTP.
Even in the case of printing by the use of printing plate materials for CTP, it has been necessary for an operator to set an individual printing condition depending on a type of printing plate material in the past, because optimum printing conditions vary depending on printing materials such as a type of ink, dampening water and printing paper in addition to types of printing plate materials and image patterns.
In particular, in the case of in-flight processing type printing plate materials representing processless printing plate materials, it is necessary to set optimum conditions constantly for keeping fixed printing quality, because exposure conditions and water-ink balance conditions in the initial printing are affected greatly by in-flight developability.
However, even when the conditions were set individually, it was impossible to avoid occurrence of a width of fluctuation to a certain extent in printing quality, because of actual fluctuations of manufacturing lot of printing plate materials, aging performance, efficiency by working environment such as temperature and humidity, or of output of exposure light source and in printing conditions.
Further, in the past, it was necessary to control developing conditions and printing conditions based on information of exposure conditions and developing conditions recorded on, for example, a sheet of paper, and it was necessary to control plate-making and printing manually, which was extremely time-consuming and errors of control were easily caused.
On the other hand, in recent years, development of RFID (wireless IC tag) has been advanced in the field of non-contact IC card.
Owing to the tendency toward a low price and downsizing of (wireless IC tag), there are known practical use as tools for production control and stock control of commodities including a field of cards having a high added value (for example, see Patent Document 4).
(Patent Document 1) TOKUKAI No. 2001-96710
(Patent Document 2) TOKUKAI No. 2001-138652
(Patent Document 3) TOKUKAI No. 2001-113848
(Patent Document 4) TOKUKAI No. 2003-67838